The Atrocity Archives by Charles Stross

Do you enjoy spy novels a la Len Deighton?  What about eldritch Lovecraftian horror?  James Bond thrillers, you say?  Well now, you can have all three, plus plenty of Pythonesque satire, in one easy-to-read volume!  But wait, there's more - real historical events, with strange, alternate explanations, and multidimensional mathematics, combined with advanced computational demonology, all at no additional cost!

Welcome to the freaky, fantabulous world of Charles Stross.  Welcome to The Laundry.  Meet new hire Bob Howard - just an ordinary cubicle mole, with an unusual gift for some rather arcane applications of higher mathematics.  After very nearly laying waste to a considerable section of Central London, Bob has been recruited into England's most secret service, The Laundry. 

A Dark Matter by Peter Straub

Peter Straub has been one of my favorite authors for a very long time.  I like the horror genre, within certain limits, but Straub goes beyond mere horror, into the rarely achieved realm of mortal dread, which is so much more effective than a good scare. 

Beyond that, he's a damned good writer in the best literary sense, with a real sense of poetry that manages to convey impressions of the eternal and the sacred, instead of just plot and character.  As such, his novels sometimes be very difficult to review, because their true value is so ethereal.